Dell PowerConnect 3424 User's Guide (.htm) - Page 28

Features Overview, Power over Ethernet, Head of Line Blocking, Flow Control Support (IEEE 802.3X)

Page 28 highlights

www.dell.com | support.dell.com Features Overview This section describes the device features. For a complete list of all updated device features, see the latest software version Release Notes. Power over Ethernet Power over Ethernet (PoE) provides power to devices over existing LAN cabling, without updating or modifying the network infrastructure. PoE removes the need for placing network devices next to power sources. PoE can be used in the following applications: • IP Phones • Wireless Access Points • IP Gateways • PDAs • Audio and video remote monitoring For more information about Power over Ethernet, see "Managing Power over Ethernet". Head of Line Blocking Head of Line (HOL) blocking results in traffic delays and frame loss caused by traffic competing for the same egress port resources. HOL blocking queues packets, and the packets at the head of the queue are forwarded before packets at the end of the queue. Flow Control Support (IEEE 802.3X) Flow control enables lower speed devices to communicate with higher speed devices, by requesting that the higher speed device refrains from sending packets. Transmissions are temporarily halted to prevent buffer overflows. For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration" or "Defining LAG Parameters." Back Pressure Support On half-duplex links, the receiving port prevents buffer overflows by occupying the link so that it is unavailable for additional traffic. For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration" or "Defining LAG Parameters." Virtual Cable Testing (VCT) VCT detects and reports copper link cabling occurrences such as open cables and cable shorts. For more information on testing cables, see "Running Cable Diagnostics". 28 Introduction

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28
Introduction
www.dell.com | support.dell.com
Features Overview
This section describes the device features. For a complete list of all updated device features, see the
latest software version
Release Notes
.
Power over Ethernet
Power over Ethernet (PoE) provides power to devices over existing LAN cabling, without updating
or modifying the network infrastructure. PoE removes the need for placing network devices next to
power sources. PoE can be used in the following applications:
IP Phones
Wireless Access Points
IP Gateways
PDAs
Audio and video remote monitoring
For more information about Power over Ethernet, see "Managing Power over Ethernet".
Head of Line Blocking
Head of Line (HOL) blocking results in traffic delays and frame loss caused by traffic competing
for the same egress port resources. HOL blocking queues packets, and the packets at the head of
the queue are forwarded before packets at the end of the queue.
Flow Control Support (IEEE 802.3X)
Flow control enables lower speed devices to communicate with higher speed devices, by requesting
that the higher speed device refrains from sending packets. Transmissions are temporarily halted to
prevent buffer overflows.
For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration"
or "Defining LAG Parameters."
Back Pressure Support
On half-duplex links, the receiving port prevents buffer overflows by occupying the link so that it is
unavailable for additional traffic.
For information on configuring Flow Control for ports or LAGs, see "Defining Port Configuration"
or "Defining LAG Parameters."
Virtual Cable Testing (VCT)
VCT
detects and reports copper link cabling occurrences such as open cables and cable shorts. For
more information on testing cables, see "Running Cable Diagnostics".